Question

我有以下数据框：

library(tidyverse)
df <- structure(list(rank = structure(c(1L, 10L, 11L, 12L, 13L, 14L, 
15L, 16L, 17L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L), .Label = c("1", 
"10", "11", "12", "13", "14", "15", "16", "17\n*", "2", "3", 
"4", "5", "6", "7", "8", "9"), class = "factor"), p_value = structure(c(2L, 
5L, 17L, 16L, 13L, 12L, 11L, 10L, 9L, 8L, 4L, 3L, 14L, 7L, 6L, 
1L, 15L), .Label = c("1e-12", "1e-12262", "1e-164", "1e-176", 
"1e-2381", "1e-26", "1e-27", "1e-274", "1e-369", "1e-397", "1e-413", 
"1e-422", "1e-429", "1e-57", "1e-6", "1e-855", "1e-919"), class = "factor")), row.names = c(NA, 
-17L), class = c("tbl_df", "tbl", "data.frame"), .Names = c("rank", 
"p_value"))

df看起来像这样：

# A tibble: 17 x 2
      rank  p_value
    <fctr>   <fctr>
 1       1 1e-12262
 2       2  1e-2381
 3       3   1e-919
 4       4   1e-855
 5       5   1e-429
 6       6   1e-422
 7       7   1e-413
 8       8   1e-397
 9       9   1e-369
10      10   1e-274
11      11   1e-176
12      12   1e-164
13      13    1e-57
14      14    1e-27
15      15    1e-26
16      16    1e-12
17 "17\n*"     1e-6

我的问题是如何将p_value列类型从fctr转换为数字，以便我可以使用它执行数学运算。

我尝试了这个错误

> df %>% mutate(logp = log(p_value))
Error in mutate_impl(.data, dots) : 
  Evaluation error: ‘log’ not meaningful for factors.

Answer 1

您可以将这些转换为这样的数字。您首先需要在数字之前将因子转换为字符，否则您只需获得数字因子级别。

df %>% mutate(logp = log(as.numeric(as.character(p_value))))

# A tibble: 17 x 3
      rank  p_value       logp
    <fctr>   <fctr>      <dbl>
 1       1 1e-12262       -Inf
 2       2  1e-2381       -Inf
 3       3   1e-919       -Inf
 4       4   1e-855       -Inf
 5       5   1e-429       -Inf
 6       6   1e-422       -Inf
 7       7   1e-413       -Inf
 8       8   1e-397       -Inf
 9       9   1e-369       -Inf
10      10   1e-274 -630.90832
11      11   1e-176 -405.25498
12      12   1e-164 -377.62396
13      13    1e-57 -131.24735
14      14    1e-27  -62.16980
15      15    1e-26  -59.86721
16      16    1e-12  -27.63102
17 "17\n*"     1e-6  -13.81551

如何使用dplyr

1 个答案: